Trove includes theses at all levels, including Ph D, masters and honours.
Trove - Australian digital theses A pre-defined search which limits the results to online Australian theses only.
I am not suggesting you become a mindless automaton who only does economics (this actually causes your grades to deteriorate). H1 at Melbourne) in almost every economics and maths class you take.
But if you want to break into the top 10, at some point you need to get invested in playing the game that is Ph D admissions. The more advanced the class is, the more important it is to get a good grade in it.
Unless you are very lucky, getting into a top program will take time and effort.
You will benefit from starting to plan for this for a few years before you apply.
For more information on rights of use and removing material in UNSWorks see Copyright - UNSWorks.
To find Australian and international theses, search via: Library collection To find theses, search for a title or keywords.
More information on UNSWorks can be found in UNSWorks guidelines For older print theses, search for a title or keywords including the term in the column on the left.
Only copies of UNSW Ph D or Masters by Research theses are held at UNSW Library.